Communication system, server device used in communication system, communication device, and program for executing communication method of the communication device

ABSTRACT

A communication system including a communication device and a server device. In a server device, a communication information memory stores unique information that is information for identifying a second communication device and communication destination information that is information for communicating with the second communication device. In a first communication device, a first server device identification information memory stores server device identification information that is information for accessing to a server device. An input receiver receives the input of unique information. When the input receiver receives the input of unique information, a first communication destination information acquisition unit accesses to the server device identified by the server device identification information, and acquires communication destination information corresponding to the unique information from server device. A first communication unit communicates with a second communication device by using the communication destination information.

TECHNICAL FIELD

The present invention relates to a communication system and the likeincluding mobile terminals.

BACKGROUND ART

Mobile IP (Internet Protocol) is known as the first communicationtechnology in a conventional communication system including mobileterminals. This technology will be described by using the communicationsystem of FIG. 11.

The communication system of FIG. 11 includes fixed terminal 1101, mobileterminal 1102, and server device 1103.

In this communication system, suppose a phone call is made from fixedterminal 1101 to mobile terminal 1102 by using IP address.

When mobile terminal 1102 moves to a space that a different network isused, fixed terminal 1101 is usually unable to communicate because ithas no information of IP address of mobile terminal 1102. However,server device 1103 has a function of getting the information of IPaddress even when mobile terminal 1102 moves to the space that thedifferent network is used.

Accordingly, fixed terminal 1101 transmits a communication packet toserver device 1103 via path 1111 and path 1112 in FIG. 11 to communicatewith mobile terminal 1102.

Next, the communication packet is transmitted from server device 1103 tomobile terminal 1102 via path 1113 and path 1114 in FIG. 11.

Further, mobile terminal 1102 directly transmits a communication packetto fixed terminal 1101 via path,1115 and path 1116 in FIG. 11.

In FIG. 11, the function of controlling the paths in server device 1103is called a home agent the function of controlling the paths in mobileterminal 1102 is called a foreign agent. Also, an exclusive line isusually employed for the network between path 1115 and path 1116 in FIG.11.

Next, the second communication technology in a communication systemincluding mobile terminals will be described in the following.

A communication system using this communication technology is shown inFIG. 12.

The communication system of FIG. 12 includes fixed terminal 1201, mobileterminal 1202, and server device 1203. In this communication system,suppose a phone call is made from fixed terminal 1201 to mobile terminal1202 by using IP address.

When mobile terminal 1202 moves to a space on a different network, fixedterminal 1201 is usually unable to communicate because it has noinformation of IP address of mobile terminal 1202. However, serverdevice 1203 has a function of getting the information of IP address evenwhen mobile terminal 1202 moves to a space of different network.

Fixed terminal 1201 transmits a communication packet to server device1203 via path 1211 and path 1212 in FIG. 12 communicate with mobileterminal 1202.

Next, the communication packet is transmitted from server device 1203 tomobile terminal 1202 via path 1213 and path 1214 in FIG. 12.

Next, mobile terminal 1202 transmits a communication packet to serverdevice 1203 via path 1215 and path 1216 in FIG. 12. Further, serverdevice 1203 transmits the communication packet to fixed terminal 1201via path 1217 and path 1218 in FIG. 12. In the second conventionaltechnology, server device 1202 maintains the IP address of fixedterminal 1201 and mobile terminal 1202.

Next, the third communication technology in a communication systemincluding mobile terminals will be described. The third communicationtechnology is a technology for communication between a mobile terminaland a mobile terminal.

A communication system using this communication technology is shown inFIG. 13.

This communication system includes first mobile terminal 1301, secondmobile terminal 1302, first server device 1303, and second server device1304.

In this communication system, suppose a phone call is made from firstmobile terminal 1301 to second mobile terminal 1302 by using IP address.

The communication packet transmitted from first mobile terminal 1301 istransmitted to first server device 1303 via path 1311 and path 1312 inFIG. 13.

Next, the communication packet is transmitted from first server device1303 to second server device 1304 via path 1313 and path 1314 in FIG.13. Next, the communication packet is transmitted from second serverdevice 1304 to second mobile terminal 1302 via path 1315 and path 1316in FIG. 13.

Thus, the communication packet is transmitted from first mobile terminal1301 to second mobile terminal 1302.

In communication packet transmission from second mobile terminal 1302 tofirst mobile terminal 1301, the communication packet follows the pathsin the opposite direction to the above.

In the third conventional technology, first server device 1303 serves tocontrol the IP address of second mobile terminal 1302, and second serverdevice 1304 serves to control the IP address of first mobile terminal1301.

First server device 1303 and second server device 1304 may be one unit(server device).

In such a case as described above, a copy of communication packet isgenerated in the server device, causing the server load to be increased.

Thus, in a communication system based on the conventional technology,the server device accesses the network every communication made by eachterminal. Accordingly, the communication traffic between server deviceand network will become massive, and it may cause congestion.

SUMMARY OF THE INVENTION

The communication system of the present invention includes a firstcommunication device, a second communication device for communicatingwith the first communication device, and a server device which accessesthe first communication device.

In the server device, the communication information memory stores uniqueinformation that is information for identifying the second communicationdevice and communication destination information that is information forestablishing communication with the second communication device.

In the first communication device, the first server deviceidentification information memory stores server device identificationinformation that is information for accessing the server device. Theinput receiver receives the input of unique information. When the inputreceiver receives the input of unique information, the firstcommunication destination information acquisition unit accesses theserver device identified by the server device identification informationand obtains the communication destination information corresponding tothe unique information from the server device. The first communicationunit uses the communication destination information to communicate withthe second communication device without using the server device.

In the communication device of the present invention, the server deviceidentification information memory stores server device identificationinformation that is information for accessing the server device. Theinput receiver receives the input of unique information. Thecommunication destination information acquisition unit accesses theserver device identified by server device identification informationwhen the input receiver receives the input of unique information, andobtains communication destination information corresponding to theunique information from the server device. The communication unit usesthe communication destination information to communicate with anothercommunication device without using the server device.

In the server device of the present invention, the communication unitcommunicates with the communication device. The communicationinformation memory stores unique information that is information foridentifying the communication device and communication destinationinformation that is information for communicating with the communicationdevice. Further, the server device transmits communication destinationinformation corresponding to the unique information of the secondcommunication device received from the first communication device to thefirst communication device.

In a program readable for a computer, by which the computer executes thecommunication method of a communication device in a communication systemincluding a server device, the communication method comprises thefollowing steps.

-   -   a) Receiving communication destination information that is        information for establishing communication with another        communication device.    -   b) Communicating with another communication device by using        communication destination information without using the server        device.    -   c) Receiving the input of unique information that is information        for identifying another communication device.

Here, in step a), communication destination information corresponding tothe unique information is acquired from the server device.

Also, information for establishing communication with the communicationdevice itself is transmitted to the server device. Here, in step a),information for communicating with the communication device itself isacquired as communication destination information.

According to the communication system, communication device, serverdevice, and program as described above, it is possible to provide acommunication system that may reduce the volume of communication betweenserver device and Internet.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a structural diagram of a communication system in thepreferred embodiment 1.

FIG. 2 is a flow chart for describing the operation of the firstcommunication device in the preferred embodiment 1.

FIG. 3 shows a table of communication information management in thepreferred embodiment 1.

FIG. 4 is a structural diagram of a communication system in thepreferred embodiment 2.

FIG. 5 is a flow chart for describing the operation of the secondcommunication device transmitting communication destination informationto the server device in the preferred embodiment 2.

FIG. 6 is a flow chart for describing the operation of the server devicereceiving and registering communication destination information in thepreferred embodiment 2.

FIG. 7 shows a table of communication information management in thepreferred embodiment 2.

FIG. 8 is a structural diagram of a communication system in thepreferred embodiment 3.

FIG. 9 is a flow chart for describing the operation of the firstcommunication device in the preferred embodiment 3.

FIG. 10 is a flow chart for describing the operation of the secondcommunication device in the preferred embodiment 3.

FIG. 11 shows the configuration of a communication system in theconventional technology.

FIG. 12 shows the configuration of a communication system in theconventional technology.

FIG. 13 shows the configuration of a communication system in theconventional technology.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

The preferred embodiments of the present invention will be described indetail in the following with reference to the drawings. In the preferredembodiments, a component element and a step in flow charts using thesame reference numeral or sign perform the same function. Therefore, thedescription of component elements and steps already described issometimes omitted.

Preferred Embodiment 1

FIG. 1 is a structural diagram of a communication system related to thispreferred embodiment. The communication system includes firstcommunication device 101, second communication device 102, and serverdevice 103. In this communication system, first communication device 101makes a call to second communication device 102. To make a call is totrigger for starting communication and to execute pre-processing forcommunication.

First communication device 101 includes first server deviceidentification information memory 10101, input receiver 10102, firstcommunication destination information memory 10103, and firstcommunication unit 10104.

First server device identification information memory 10101 storesserver device identification information that is information foraccessing to server device 103. The server device identificationinformation may be any information used to gain access to server device103, for example, an IP address of server device 103 or electronic mailaddress for information to be received by server device 103. Here, theIP address may be any one of IP address of IP Ver4, IP address of IPVer6 and the like.

First server device identification information memory 10101 can berealized by non-volatile recording medium or volatile recording medium.

Input receiver 10102 receives the input of unique information of secondcommunication device 102. The unique information is, for example, atelephone number. Also, the unique information may be an electronic mailaddress, name or nickname of communication destination and the like.Receiving the input of unique information is executed by various methodssuch as receiving the input of unique information made by ten-key andreceiving the input made by menu selection.

Input receiver 10102 may be realized by a keyboard and its driversoftware or a mouse and its driver software and menu processingsoftware.

When input receiver 10102 receives the input of unique information,first communication destination information acquisition unit 10103accesses to server device 103 identified by server device identificationinformation and obtains communication identification information to bematched with the unique information, that is, the information forming apair with the unique information from server device 103. Any algorithmmay be used for obtaining communication destination information fromserver device 103.

First communication destination information acquisition unit 10103 maytake communication destination information out of server device 103 byretrieving the information of server device 103.

First communication destination information acquisition unit 10103 mayinstruct server device 103 to transmit the communication identificationinformation matched with the unique information and to receive thecommunication destination information transmitted from server device 103according to the instruction.

First communication identification information acquisition unit 10103 isusually realized by software, but it may be realized by hardware such asan exclusive line.

First communication unit 10104 communicates with second communicationdevice 102 by using communication destination information obtained byfirst communication destination information acquisition unit 10103without communicating via server device 103.

Second communication device 102 includes second communication unit10201.

Second communication unit 10201 establishes communicates with firstcommunication device 101 without communicating via the server device.

First communication unit 10104 and second communication unit 10201 canbe realized by a both-directional wireless or cable communicationdevice.

Server device 103 includes communication information memory 10301.

Also, server device 103 includes a communication unit and a control unitbeing not shown. The communication unit communicates with thecommunication device (the second communication device in this preferredembodiment). The control unit controls the server device.

Communication information memory 10301 stores unique information that isinformation for identifying second communication device 102 andcommunication information having communication destination informationthat is information for communicating with second communication device102. Communication information is, for example, an IP address. Also, anIP address may be any one of IP address of IP Ver4, IP address of IPVer6 and the like.

Communication information storage 10301 can be realized by non-volatilerecording medium or volatile recording medium.

The operation of this communication system will be described in thefollowing.

First, the operation of first communication device 101 is described byusing the flow chart of FIG. 2.

(Step S201) It is judged whether input receiver 10102 has received theinput of unique information of second communication device 102. In caseit has received the input of unique information, it goes to step S202,and if it has not received the input of unique information, then stepS201 is repeated.

(Step S202) First communication destination information acquisition unit10103 acquires the first server device identification information storedin first server device identification information memory 10101.

(Step S203) First communication destination information acquisition unit10103 accesses the sever device identified by the first serveridentification information acquired in step S202 and obtainscommunication destination information according to the uniqueinformation received in step S201.

(Step S204) First communication unit 10104 obtains communicationdestination information acquired in step S203.

(Step S205) First communication unit 10104 communicates with secondcommunication device 102. To establish the communication, a call isestablished as initial processing, and a process is executed to attain astatus that enables communication. After the initial processing is oncemade, the information is transmitted and received in both directions.

(Step S206) First communication unit 10104 judges whether input receiver10102 or first communication unit 10104 has received a terminationsignal. In case it has received a termination signal, the step isterminated, and if it has not received a termination signal, then theprocess returns to step S205. If it returns to step S205 in a state ofcommunication, initial processing will not be executed.

In the flow chart of FIG. 2, unique information received by inputreceiver 10102 is the unique information of second communication device102 in the above description. It is intended to make the descriptioneasier in the preferred embodiment.

Unique information received by input receiver 10102 may be anyinformation provided that it is the unique information of thecounterpart to communicate with.

The operation of second communication device 102 is described in thefollowing.

Second communication device 102 communicates with first communicationdevice 101. In detail, it responds to the request for communication fromfirst communication device 101 and opens a call to enter into a state ofcommunication. After entering into a state of communication, secondcommunication device 102 transmits and receives information to and fromfirst communication device 101 in both directions.

As for second communication device 102, in the configuration of FIG. 1,shown is only the function of receiving a request for communication fromfirst communication device 101 and communicating with firstcommunication device 101.

However, the configuration of second communication device 102 of FIG. 1is a simplified configuration for making easier the description of thepreferred embodiment. That is, second communication device 102 usuallyincludes a configuration similar to that of first communication device101. Therefore, the communication can be started by designating thecounterpart from second communication device 102.

That is, second communication device 102 also may include an inputreceiver, a server device identification information memory equivalentto the first server device identification information memory, and acommunication destination information acquisition unit equivalent to thefirst communication destination information acquisition unit.

The operation of server device 103 is described in the following.

Server device 103 gives communication destination information to firstcommunication device 101 according to the request from firstcommunication device 101. Any algorithm may be employed for givingcommunication destination information to first communication device 101.For example, server device 103 receives a communication destinationinformation transmitting command from first communication device 101.The transmitting command includes unique information. Here, serverdevice 103 retrieves communication destination information to be a pairwith the unique information. Further, server device 103 transmitscommunication destination information to first communication device 101.

The operation of the communication system in this preferred embodimentis specifically described in the following.

Here, the first communication device and the second communication deviceare mobile portable telephones.

The server device stores communication information shown in FIG. 3. FIG.3 is a table of communication information management.

In FIG. 3, unique information is a telephone number, and communicationdestination information is an IP address of IP Ver6.

Also, assume that unique information of the second communication deviceis “010-2222-3333.” That is, the second communication device is IPtelephone using Internet.

The second communication device moves, and the communication destinationinformation of the second communication device changes according to themovement. Assume that the communication destination information changedin accordance with the movement of the second communication device is“1080::8:800:200C:417A.” Here, “1080::8:800:200C:417A.” is arepresentation using the abbreviation of IP address of IP Ver6.

Also, an example of algorithm for providing the server device withcommunication destination information changed in accordance with themovement of the second communication device will be described in thepreferred embodiment 2. Here, any algorithm is preferable for providingthe server device with communication destination information changed inaccordance with the movement of the second communication device.

In such a case, the user of the first communication device inputs thetelephone number “1010-2222-3333” to the first communication device tospeak with the user of the second communication device.

Next, the first communication device receives the input of telephonenumber “010-2222-3333”, and obtains server device identificationinformation for identifying the server device from the first serverdevice identification information memory. Here, the first server deviceidentification information memory stores an IP address “24FE:1:503::4”(abbreviated expression in IP Ver6) assigned to the server device.

Next, the first communication device obtains an IP address“24FE:1:503::4” from the first server device identification informationmemory.

Subsequently, the first communication device transmits a sending commandfor transmitting communication destination information to the serverdevice identified by an IP address “24FE:1:503::4”. The sending commandincludes the telephone number “010-2222-3333.”

Next, the server device receives the sending command.

Subsequently, the server device fetches telephone number “010-2222-3333”included in the sending command.

Next, the server device fetches communication destination information tobe matched with the telephone number “010-2222-3333.” That is, theserver device obtains communication destination information“1080::8:800:200C:417A” to be matched with the telephone number“010-2222-3333” from the table of communication information managementof FIG. 3.

Next, the server device transmits communication destination information“1080::8:800:200C:417A” to the first communication device.

Subsequently, the first communication device receives communicationdestination information “1080::800:200C:417A.”

Next, the first communication device makes a call to the secondcommunication device identified by communication destination information“1080::8:800:200C:417A.”

The second communication device receives a request for communicationfrom the first communication device, then a call is established betweenboth communication devices, and the bidirectional communication isstarted between both communication devices.

Thus, bidirectional communication, that is, a talk by telephone isestablished until a communication ending signal is input from either theuser of the first communication device or the user of the secondcommunication device.

As described above, according to the present preferred embodiment, incommunication with a mobile communication device, it enables thebidirectional communication and prevents the traffic of network frombecoming too much expanded.

Specifically, it is possible to greatly reduce the number ofcommunications and the amount of communication data between the serverthat manages the communication destination information of mobilecommunication device and Internet, thereby preventing the increase oftraffic.

In the present preferred embodiment, communication destinationinformation has been described by using an IP address of IP Ver6 as anexample, but the communication destination information used may be anyinformation for establishing communication with a communication devicesuch as an IP address of IP Ver4. The same holds true in other preferredembodiments.

Also, in the present preferred embodiment, the unique information hasbeen described by using a telephone number as an example, but the uniqueinformation may be information such as the nickname of the user of thecommunication device. The same holds true in other preferredembodiments.

Also, in the present preferred embodiment, any algorithm is preferablefor the first communication device to obtain communication destinationinformation. The same holds true in other preferred embodiments.

Further, regarding the operation of the first communication device, thesecond communication device and the server device described in thepresent preferred embodiment, the operation may be realized with use ofsoftware.

By putting the software on a server for example, it may be used todistribute the software by software download. Further, it may beperformed to distribute the software recorded in a recording medium suchas CD-ROM. The same holds true in all the preferred embodiments.

Preferred Embodiment 2

FIG. 4 is a structural diagram of a communication system in thispreferred embodiment. The communication system includes firstcommunication device 101, second communication device 402, and serverdevice 403. In this communication system, a call is made from firstcommunication device 101 to second communication device 402.

Second communication device 402 includes second communication unit 1020,second communication destination information acquisition unit 40201,second server device identification information memory 40202, andcommunication destination information transmitter 40203.

Second communication destination information acquisition unit 40201acquires communication destination information that is information forestablishing communication with second communication device 402.

Any method is preferable for second communication destinationinformation acquisition unit 40201 to obtain communication destinationinformation.

Second communication destination information acquisition unit 40201receives, for example, communication destination information from anexternal device of a wireless communication base station. The way ofrealizing second communication destination information acquisition unit40201 varies with the method of acquiring communication destinationinformation. Second communication destination information acquisitionunit 40201 is, for example, realized by a wireless communication device.

Second server device identification information memory 40202 storesserver device identification information that is information foraccessing to server device 403. Any server device identificationinformation is preferable, if the information is for accessing to serverdevice 403. Server device identification information is, for example,the IP address of server device 403 or an electronic mail address fordelivering the information to server device 403. Also, the IP addressmay be any address such as an IP address of IP Ver4 or an IP address ofIP Ver6.

Second server device identification information memory 40202 can berealized by non-volatile recording medium or volatile recording medium.

Communication destination information transmitter 40203 transmitscommunication destination information acquired by second communicationdestination information acquisition unit 40201 to server device 403identified by server device identification information. Communicationdestination information transmitter 40203 can be usually realized by awireless communication device.

Here, second communication unit 10201 usually has a function ofreceiving communication destination information from a wirelesscommunication base station.

In second communication device 402, it is preferable to realize secondcommunication unit 10201, second communication destination informationacquisition unit 40201, and communication destination informationtransmitter 40203 with physically one wireless communication device.

Second communication device 402 has been described above, but asdescribed in the preferred embodiment 1, first communication device 101may be configured in the same structure as second communication device402. Accordingly, first communication device 101 may have the samefunctions as those of second communication device 402. Here, firstcommunication destination acquisition unit 10103 and secondcommunication destination acquisition unit 40202 acquire communicationdestination information that is information for communicating with thecommunication device itself, and also acquire communication destinationinformation of the communication counterpart from server device 403.

Also, second communication device 402, as described in the preferredembodiment 1, may include an input receiver.

Server device 403 includes communication information memory 10301,communication destination information receiver 40301, and communicationdestination updating unit 40302. That is, communication destinationinformation receiver 40301 and communication destination informationupdating unit 40302 are added to the configuration of the preferredembodiment 1.

Communication destination information receiver 40301 receivescommunication destination information from second communication device402. Communication destination information receiver 40301 can berealized by a wireless or cable communication device.

Communication destination information updating unit 40302 registers thecommunication destination information received by communicationdestination information receiver 40301 as updated communicationdestination information of communication information memory 10301. Here,to register means, for example, overwriting the received communicationdestination with respect to communication destination information storedin communication information memory 10301. Communication destinationinformation updating unit 40302 can be usually realized by software, butit may be realized by using hardware such as an exclusive circuit.

The operation of the communication system will be described in thefollowing.

First, the operation of second communication device 402 for transmittingcommunication destination information to server device 403 is describedby using the flow chart of FIG. 5.

(Step S501) It is judged whether second communication destinationinformation acquisition unit 40201 has acquired the communicationdestination information of second communication device 402 itself. Incase it has acquired the communication destination information, it goesto step S502, and if it has not acquired the communication destinationinformation, then step S501 is repeated.

(Step S502) Communication destination information transmitter 40203takes out server device identification information from second serverdevice identification information memory 40202.

(Step S503) Communication destination information transmitter 40203transmits communication destination information obtained in step S501 tothe server device identified by server device identification informationfetched in step S502.

In the flow chart of FIG. 5, with communication destination obtained,the communication destination is always transmitted to the serverdevice.

Also, the second communication device judges whether the communicationdestination information of the second communication device itself ischanged, and only when changed, the second communication device maytransmit the communication destination information to the server device.In that case, second communication device 402 is configured as describedin the following.

Further, there is provided a change detector not shown which detects thechange of communication destination information that is information forcommunicating with second communication device 402. Communicationdestination information transmitter 40203 transmits communicationdestination information to server device 403 when the change detectordetects the change of communication destination information.

Also, in the flow chart of FIG. 5, nothing is mentioned about a casethat communication destination information is obtained, butcommunication destination information may be acquired periodically.Also, only when communication destination information is changed due toa movement of the second communication device, communication destinationinformation may be acquired by transmitting communication destinationinformation from a base station or the like to the second communicationdevice.

Further, communication destination information transmitter 40203 usuallytransmits unique information of second communication device 402 togetherwith communication destination information to server device 403. Serverdevice 403 rewrites the communication information that corresponds, thatis, matches with the unique information.

Next, the operation of server device 403 for receiving and registeringcommunication destination information will be described by using theflow chart of FIG. 6.

(Step S601) It is judged whether communication destination informationreceiver 40301 has received communication destination information. Incase it has received communication destination information, it goes tostep S602, and if it has not received communication destinationinformation, then step S601 is repeated.

(Step S602) Communication destination information updating unit 40302retrieves the portion of registering the communication destinationinformation received in step S601. The registering portion exists incommunication information memory 10301. Here, retrieving the registeringportion means, for example, executing the following processing.

Communication destination information receiver 40301 receives, forexample, the communication destination information and the uniqueinformation of second communication device 402 in the form of a pair.Further, communication destination information updating unit 40302obtains communication information including communication destinationinformation, by using the received unique information as a key.

(Step S603) Communication destination information updating unit 40302registers the communication destination information received in stepS601 in the registering portion retrieved in step S602.

The operation of the communication system in the present preferredembodiment will be specifically described in the following.

Here, the first communication device and the second communication deviceare mobile portable telephones.

The server device stores communication information shown in FIG. 3.Also, assume that unique information of the second communication deviceis “010-2222-3333.” That is, the second communication device is an IPtelephone using Internet.

Here, the second communication device moves, and the communicationdestination information of the second communication device changesaccording to the movement. Assume that the communication destinationinformation of the second communication device changed in accordancewith the movement of the second communication device is“1080::5:2A11:11DE:555C.”

The second communication device receives, for example, an IP address“1080::5:2A11:11DE:555C” assigned to the second communication devicefrom a wireless communication base station of the destination. Then, thesecond communication device transmits the received IP address“1080::5:2A11:11DE:555C” to the server device. In transmission, thesecond communication device also transmits its unique information“010-2222-3333” to the server device.

The server device receives the IP address “1080::5:2A11:11DE:555C” andthe unique information “010-2222-3333” from the second communicationdevice. Subsequently, the server device changes communicationdestination information corresponding to the unique information“010-2222-3333” of the table (communication information managementtable) for the management of communication information of FIG. 3 into“1080::5:2A11:11DE:555C.” As a result, the communication informationmanagement table becomes as shown in FIG. 7.

The second communication device may transmit communication destinationinformation to the server device when the change of the communicationdestination information is detected by the change detector. Also, thesecond communication device may always transmit communicationdestination information to the server device when it acquirescommunication destination information.

Also, the server device may always register the communicationdestination information received from the second communication device.Also, the server device compares the communication destinationinformation stored in the communication information memory with thecommunication destination information, and there is a difference betweenthe two, to the server device may register the communication destinationinformation received.

As described above, according to the present preferred embodiment, incommunication with a mobile communication device, it is possible to makebidirectional communication in both directions and to prevent thetraffic of network from becoming too much expanded. In addition, theserver device receives communication destination information from thesecond communication device which are moving, and the server device isalways able to maintain the communication destination information of theplace at which the second communication device moves. Accordingly,wherever the second communication device moves, the first communicationdevice is able to properly establish communication with the secondcommunication device.

Preferred Embodiment 3

FIG. 8 is a structural diagram of a communication system in thispreferred embodiment.

The communication system includes first communication device 801, secondcommunication device 802, and server device 403. In this communicationsystem, a call is made from first communication device 801 to secondcommunication device 802.

Server device 403 is configured in the same structure as in thepreferred embodiment 2.

First communication device 801 includes first server deviceidentification information memory 10101, input receiver 10102, firstcommunication destination information acquisition unit 10103, firstcommunication unit 80103, communication destination information receiver80101, and communication controller 80102.

Communication destination information receiver 80101 receivescommunication destination information from second communication device802 during the communication with second communication device 802.Communication destination information receiver 80101 is usually realizedby a wireless communication device.

Communication controller 80102 instructs first communication unit 10104to change over the destination to the destination shown by the receivedcommunication destination information when communication destinationinformation receiver 80101 receives new communication destinationinformation. Communication controller 80102 can be usually realized bysoftware, but it may be realized by hardware (an exclusive circuit).

First communication unit 80103 establishes communication with secondcommunication device 802. Also, when new communication destinationinformation is received from communication controller 80102 during thecommunication, the communication is made by changing it over to thedestination shown by the new communication destination information.First communication unit 80103 can be usually realized by wirelesscommunication device. First communication unit 80103 includes softwareor the like for communicating by changing it over to the destinationshown by the new communication destination information.

Second communication device 802 includes second communication unit10201, second communication destination information acquisition unit40201, second server device identification information memory 40202,change detector 80201, and communication destination informationtransmitter 80202.

Change detector 80201 detects that the change of the communicationdestination information of second communication device 802 itself. Anymethod for detecting the change may be employed. Change detector 80201receives communication destination information from a base station forwireless communication, for example, only when the communicationdestination information of second communication device 802 itself ischanged. Also, change detector 80201 receives communication destinationinformation from a wireless communication base station for exampleperiodically or at all times, and compares the last communicationdestination information being stored with the communication destinationinformation received, and if both do not coincide with each other, it isjudged that the communication destination information is changed.

Change detector 80201 is usually realized by software, but it may berealized by hardware.

Here, second communication unit 10201 usually has a function ofreceiving communication destination information from a wirelesscommunication base station.

Communication destination information transmitter 80202 transmitscommunication destination information acquired by second communicationdestination information acquisition unit 40201 to first communicationdevice 801 when the change of communication destination information isdetected by change detector 80201 during communication with firstcommunication device 801.

Also, communication destination information transmitter 80202 transmitsthe communication destination information acquired by secondcommunication destination information acquisition unit 40201 to serverdevice 403 as well, when change detector 80201 detects the change ofcommunication destination information. Since second communication device802 and first communication device 801 are communicating with eachother, communication destination information transmitter 80202 is ableto transmit the new communication destination information to firstcommunication device 801.

Also, the server device identification information of server device 403is obtained from second server device identification information memory40202.

Communication destination information 80202 is usually realized by awireless communication device.

The operation of the communication system will be described in thefollowing.

First, the operation of first communication device 801 is described byusing the flow chart of FIG. 9.

Here, first communication device 801 obtains communication destinationinformation of second communication device 802 from second communicationdevice 802 during communication with second communication device 802.Thus, the communication is continued between first communication device801 and second communication device 802.

The operation of first communication device 801 for startingcommunication with second communication device 802 is preformed in thesame manner as the operation described by using the flow chart of FIG.2, and the description is omitted.

(Step S901) Communication destination information receiver 80101 judgeswhether it has received communication destination information fromsecond communication device 802 during the communication with secondcommunication device 802. In case it has received communicationdestination information, it goes to step S902, and if it has notreceived communication destination information, then step S901 isrepeated.

(Step S902) Communication controller 80102 instructs first communicationunit 10104 to change over the destination to the destination shown bythe communication destination information received.

(Step S903) First communication unit 80103, during communication withsecond communication device 802, changes over the communicationdestination information of second communication device 802 to newcommunication destination information in order to continue thecommunication with second communication device 802.

Such processing is usually executed according to the followingprocedure.

First communication unit 80103 finishes calling to second communicationdevice 802 shown by the previous communication destination information,and makes a call to second communication device 802 shown by the newcommunication destination information to resume the communication withsecond communication device 802. That is, first communication unit 80103immediately resumes the communication after once finishingcommunication. Because the processing speed is very fast, the users offirst communication device 801 and second communication device 802 willfeel like that the communication is made continuously.

Next, the operation of second communication device 802 will be describedby using the flow chart of FIG. 10.

Here, second communication device 802 transmits communicationdestination information to first communication device 801 duringcommunication with first communication device 801. Thus, thecommunication is continued between first communication device 801 andsecond communication device 802.

(Step S1001) Second communication destination information acquisitionunit 40201 acquires communication destination information of secondcommunication device 802 itself. Any method is preferable for secondcommunication destination information acquisition unit 40201 to obtaincommunication destination information. For example, second communicationdestination information acquisition unit 40201 periodically receivescommunication destination information from a wireless communication basestation located in the neighborhood.

(Step S1002) Change detector 80201 compares the latest communicationdestination information with communication destination informationreceived in step S1001, and judges whether the communication destinationinformation of second communication device 802 is changed.

In case the communication destination information is changed, theprocess goes to step S1003, and if the communication destinationinformation is not changed, then it returns to step S1001.

Here, second communication device 802 always stores the latestcommunication destination information (current communication destinationinformation). That is, second communication device 802 records the newcommunication destination information as the current communicationdestination information when the communication destination informationis changed.

(Step S1003) Communication destination information transmitter 80202transmits the communication destination information acquired in stepS1001 to first communication device 801. Second communication device 802is able to transmit the communication destination information becausesecond communication device 802 are communicating with firstcommunication device 801.

(Step S1004) Communication destination information transmitter 80202obtains server device identification information from second serverdevice identification information memory 40202.

(Step S1005) Communication destination information transmitter 80202transmits the communication destination information obtained in stepS1001 to server device 403 identified by the server deviceidentification information obtained in step S1004.

After that, the process returns to step S1001.

In the flow chart of FIG. 10, when second communication device 802 hasreceived a termination signal, the operation is terminated because ofinterruption.

Also, in the flow chart of FIG. 10, change detector 80201 detects thechange of communication destination information.

Also, communication destination information may be processed in thefollowing way.

Only when the communication destination information of secondcommunication device 802 changes, second communication device 802obtains communication destination information from the outside. In thatcase, second communication device 802 may transmit communicationdestination information to first communication device 801 and serverdevice 403 without making any judgment.

Further, in the flow chart of FIG. 10, when first communication device801 and second communication device 802 are communicating with eachother, second communication device 802 transmits new communicationdestination information to server device 403. Also, after thetermination of communication, second communication device 802 maytransmit new communication destination information to server device 403.

First communication device 801 and second communication device 802 havebeen described above.

As described in the preferred embodiments 1 and 2, first communicationdevice 801 and second communication device 802 may have the sameconfiguration.

Accordingly, first communication device 801 may further include acommunication destination information transmitter equivalent tocommunication destination information transmitter 80202 and a changedetector equivalent to change detector 80201.

Also, second communication device 802 may further include an inputreceiver equivalent to input receiver 10102, a communication destinationinformation receiver equivalent to communication destination informationreceiver 80101, and a communication controller equivalent tocommunication controller 80102.

The operation of the communication system in the present preferredembodiment will be specifically described in the following.

Here, the first communication device and the second communication deviceare mobile portable telephones.

The server device stores communication information shown in FIG. 3.

Assume that the unique information of the second communication device is“010-2222-3333.” That is, the second communication device operates as anIP telephone using Internet.

Here, assume that the first communication device and the secondcommunication device are communicating with each other, and that thesecond communication device moves. The communication destinationinformation of the second communication device changes in accordancewith the movement of the second communication device. Suppose that thecommunication destination information of the second communication devicechanged in accordance with the movement is “1080::5:2A11:11DE:555C.” Thesecond communication device for example receives IP address“1080::5:2A11:11DE:555C” assigned to the second communication devicefrom a wireless communication base station of the area to which thesecond communication device has moved. Subsequently, the secondcommunication device transmits the received IP address“1080::5:2A11:11DE:555C” to the first communication device with which itis communicating. Also, the second communication device transmits thereceived IP address “1080::5:2A11:11DE:555C” to the server device aswell.

The first communication device receives a new IP address of the secondcommunication device, and changes over the destination to the new IPaddress “1080::5:2A11:11DE:555C” to continue the communication.

Also, the server device changes the communication information managementtable to the one shown in FIG. 7 as described in the preferredembodiment 2.

As described above, according to the present preferred embodiment, incommunication with a mobile communication device, it is possible toestablish communicate in both directions. Also, it is possible toprevent the traffic of network from becoming too much expanded. Further,even when communication destination is changed due to the movement ofthe communication device, a state of stable communication can becontinuously obtained.

Industrial Applicability

According to the present invention, the amount of communication trafficbetween server device and Internet can be reduced, and it is possible toprovide a communication system being free from problems such ascongestion.

1. A communication system, comprising: a first communication device, asecond communication device communicating with the first communicationdevice, and a server device being accessed by the first communicationdevice, wherein the server device includes: a communication informationmemory for storing unique information that is information foridentifying the second communication device and communicationdestination information that is information for communicating with thesecond communication device, and the first communication deviceincludes: a first server device identification information memory forstoring server device identification information that is information foraccessing the server device, an input receiver for receiving an input ofthe unique information, a first communication destination informationacquisition unit which accesses to the server device identified by theserver device identification information to acquire the communicationdestination information corresponding to the unique information from theserver device, when the input receiver receives the input of the uniqueinformation, a first communication unit which communicates with thesecond communication device by using the communication destinationinformation, and the second communication device includes: a secondcommunication unit which communicates with the first communicationdevice without using the server device.
 2. The communication system ofclaim 1, wherein the second communication device further includes: asecond communication destination information acquisition unit whichacquires another communication destination information for establishingcommunication with the second communication device, a second serverdevice identification information memory which stores the server deviceidentification information, and a communication destination informationtransmitter which transmits the another communication destinationinformation acquired by the second communication destination informationacquisition unit to a server device identified by the server deviceidentification information, and the server device further includes: acommunication destination information receiver which receives theanother communication destination information from the secondcommunication device, and a communication destination informationupdating unit which registers the another communication destinationinformation as updated communication destination information in thecommunication information memory.
 3. The communication system of claim2, wherein the second communication device further includes: a changedetector for detecting that the another communication destinationinformation is changed, and the communication destination informationtransmitter transmits the changed another communication destinationinformation to the server device when the change of the othercommunication destination information is detected by the changedetector.
 4. The communication system of claim 1, wherein the secondcommunication device further includes: a second communicationdestination information acquisition unit which acquires anothercommunication information that is information for communicating with thesecond communication device, a change detector for detecting that theanother communication destination information is changed, and acommunication destination information transmitter which transmits thechanged another communication destination information to the firstcommunication device when the change of the another communicationdestination information is detected by the change detector duringcommunication with the first communication device, and the firstcommunication device further includes: a communication destinationinformation receiver which receives the changed another communicationdestination information during communication with the secondcommunication device, and when the another communication destinationinformation is changed, communication is continued between the firstcommunication device and the second communication device.
 5. Thecommunication system of claim 1, wherein the communication destinationinformation is an IP address.
 6. The communication system of claim 2,wherein the communication destination information is an IP address andthe another communication destination information is an IP address.
 7. Acommunication device to be used for a communication system including aserver device including: a server device identification informationmemory which stores server device identification information that isinformation for accessing the server device, an input receiver whichreceives an input of unique information that is information foridentifying another communication device, a communication destinationinformation acquisition unit which gains access to a server deviceidentified by the server device identification information when theinput of the unique information is received by the input receiver, andacquires communication destination information that is information forcommunicating with the another communication device corresponding to theunique information from the server device, and a communication unit forcommunicating with the another communication device by using thecommunication destination information without using the server device.8. The communication device of claim 7, further comprising: acommunication destination information receiver which receives anothercommunication destination information of the another communicationdevice during communication with the another communication device,wherein the communication with the another communication device iscontinued when the another communication destination information of theanother communication device is changed.
 9. The communication system ofclaim 7, wherein the communication destination information is an IPaddress.
 10. The communication system of claim 8, wherein thecommunication destination information is an IP address and the anothercommunication destination information is IP address.
 11. A communicationdevice to be used for a communication system including a server device,comprising: a communication unit for communicating with anothercommunication device, a communication destination informationacquisition unit which acquires communication destination informationthat is information for establishing communication with the anothercommunication device, a server device identification information memorywhich stores server device identification information for identifyingthe server device, a communication destination information transmitterwhich transmits the communication destination information acquired bythe communication destination information acquisition unit to the serverdevice identified by the server device identification information. 12.The communication device of claim 11, further comprising: a changedetector for detecting that the communication destination information ischanged, wherein the communication destination information transmittertransmits the changed another communication destination information tothe server device when the change of the another communicationdestination information is detected by the change detector.
 13. Thecommunication device of claim 11, further comprising: a change detectorfor detecting that the communication destination information is changed,and a communication destination information transmitter which transmitsthe changed communication destination information to the anothercommunication device when the change of the communication destinationinformation is detected by the change detector during communication withthe another communication device, wherein communication with the anothercommunication device is continued when the communication destinationinformation is changed.
 14. The communication device of claim 11,wherein the communication destination information is an IP address. 15.A sever device used in a communication system, comprising: acommunication unit for communicating with a communication device, and acommunication information memory which stores unique information that isinformation for identifying the communication device, and communicationdestination information that is information for communicating with thecommunication device, wherein the server device transmits communicationdestination information corresponding to unique information of a secondcommunication device received from a first communication device to thefirst communication device.
 16. The server device of claim 15, furthercomprising: a communication destination information receiver whichreceives communication destination information of the secondcommunication device from the second communication device, and acommunication destination information updating unit which updates thecommunication destination information of the second communication devicestored in the communication information memory when the communicationdestination updating unit receives the communication destinationinformation of the second communication device.
 17. The server device ofclaim 15, wherein the communication destination information is IPaddress.
 18. A program that is readable for a computer to execute acommunication method of a communication device in a communication systemincluding a server device, wherein the communication method includes thesteps of: a) receiving communication destination information that isinformation for communicating with another communication device, and b)communicating with the another communication device by using thecommunication destination information without using the server device.19. The program of claim 18, wherein the communication method furtherincludes the step of: c) receiving the input of unique information thatis information for identifying the another communication device, whereinin step a), the communication destination information corresponding tothe unique information is obtained from the server device.
 20. Theprogram of claim 18, wherein the communication method further includesthe step of: d) transmitting information for communicating with thecommunication device itself to the server device, and in step a), theinformation for communicating with the communication device itself isobtained as the communication destination information.
 21. Thecommunication system of claim 3, wherein the communication destinationinformation is an IP address and the another communication destinationinformation is an IP address.
 22. The communication system of claim 4,wherein the communication destination information is an IP address andthe another communication destination information is an IP address. 23.The communication device of claim 12, wherein the communicationdestination information is an IP address.
 24. The communication deviceof claim 13, wherein the communication destination information is an IPaddress.
 25. The server device of claim 16, wherein the communicationdestination information is IP address.